Numbers 21:2

And Israel vowed a vow unto the LORD, and said, If thou wilt indeed deliver this people into my hand, then I will utterly destroy their cities.

Israel vowed a vow. Made to feel their own weakness, they implored the aid of Heaven, and, in anticipation of it, devoted the cities of this king to future destruction. The nature and consequence of such anathemas are described, Leviticus 27:1; Deuteronomy 13:1. This vow of extermination against Arad gave name to the place Hormah (slaughter and destruction), though it was not accomplished until after the passage of the Jordan (Joshua 12:14.)

I will utterly destroy - х wªhacharamtiy (H2763), I will anathematize, put under a curse; Septuagint, anathematioo.] In the exterminating wars with the Canaanites, vows of this description were frequently made; and in consequence, on the capture of the cities so doomed, not only were the inhabitants, both man and beast, put to the sword, but the towns themselves razed to the foundations, that nothing belonging to them might be redeemed from the vow.